Quantum Cryptography课件.ppt

Paraty, Quantum Information School, August 2007;Quantum Information Theory (QIT) studies how information can be transmitted and processed when encoded on quantum states. New information applications are possible because of quantum features: communication complexity and computational speed-up, secure information transmission and quantum teleportation. The key resource for all these applications is quantum correlations, or entanglement. A pure state is entangled whenever it cannot be written in a product form: A mixed state is entangled whenever it cannot be obtained by mixing product states: ;Quantum Information Theory;Quantum Superpositions;Entanglement and Bell’s inequalities;Entanglement and Bell’s inequalities;Quantum Cryptography: a new form of security;Quantum Cryptography: a new form of security;Quantum Key Distribution (QKD);The Quantum Bit;Heisenberg Uncertainty Relation;The no-cloning theorem;The no-cloning theorem;Basics of Quantum Cryptography;BB84 (Bennett Brassard);BB84 (Bennett Brassard);BB84 (Bennett Brassard);Other protocols;Other protocols;Other protocols;Ekert protocol;Ekert protocol;Entanglement vs Prepare Measure;Entanglement vs Prepare Measure